What is the value of 24kt gold plated state quarters from 1999 to 208?

The gold plating is only a few atoms thick and would cost more to remove than it's worth.

Unfortunately there's almost no aftermarket for these so-called "collectibles". It's almost a dead-cert that the coins are all circulation strikes, and the gold plating means that regular numismatists considered them to be altered coins - i.e. worth face value only.